Australia: The Land Where Time Began

A biography of the Australian continent 

Emergence of Early Tetrapods

According to clack¹ over the last 15 years or so the study of tetrapods and related forms that span the so-called ‘fish-tetrapod’ transition has expanded almost exponentially. There are now at least 9 named genera of tetrapod from the Devonian that represent this evolutionary event, as well as several new ‘near tetrapods’ and some new tetrapods from the Early Carboniferous. There has now been a radical change in ideas about how this transition occurred based on the anatomy of Acanthostega, and more recently some startling conclusions have been reached following reassessment of the anatomy of Ichthyostega, including the unique construction of its ear region. In this paper Clack¹ has summarised the current state of research on this range of animals, and the acquisition of limbs and digits among tetrapods, including possible forerunners, the development of digits and their original function and the onset of pentadactyly. She also brings together the faunal relations and the palaeoecological contexts of the tetrapods from the Devonian in a brief, initial survey, and an assessment of the diversity of tetrapods in the Devonian, which is now believed to be much greater than previously realised, and some thoughts on future research.

Sources & Further reading

1. Clack, J.A., (2006). "The emergence of early tetrapods." Palaeogeogr. Palaeoclimatol. Palaeoecol. 232: 167.